Ventilation System for Underground Environments

Description

FIELD OF THE INVENTION

This invention relates to ventilation systems for underground environments.

BACKGROUND OF THE INVENTION

Activities carried out in underground environments, including mining, construction, and maintenance, require ventilation for the health and safety of people and to remove pollutants and particles generated from the excavation, such as gases from internal combustion engines, from explosive detonation, from welding, from chemical reactions and also particles such as dust, grinding residue. A typical arrangement for an underground ventilation system is shown in FIG. 1.

Referring to FIG. 1, the underground space where human activity is being performed receives clean air through a ventilation duct. The clean air is collected from the surface or from another underground space and is moved by a fan. The quantity of air required depends on the amounts of pollutants generated and the number of people working underground. It is common that one fan is used to provide the ventilation for more than one region, so duct split pieces are used to divide the air flow into two or more separate ducts as shown in FIGS. 2-4.

In the case of multiple ducts as shown in FIG. 2, the amount of airflow in each duct depends on the pressure loss in each branch. Therefore, in order to control the amount of airflow in each duct, it is necessary to add a resistance to the branch(es) that require(s) less air. This additional resistance can be produced by the use of dampers, valves, or simply by reducing the cross-section of the duct. A sketch of a typical arrangement with the current technology is shown in FIG. 3.

Referring now to FIG. 3, the fan is typically powered by a drive which allows the starting and stopping of the fan. The drive panel can include a variable frequency drive that allows the control of the rotation speed of the fan. As the airflow from the fan depends on its rotation speed, the variable frequency drive allows the control of the airflow generated by the fan.

As the actual underground operations, the activities performed, and number of people involved can change with time, for example between shifts or between different stages of excavation such as drilling and blasting, the airflow required in each duct branch also changes with time. Additionally, as the operations underground are performed, especially in the cases of mining and excavation, the length of the ducts must be changed as the underground activity region extends farther and farther from the duct outlet. This changes the pressure loss in each duct branch and consequently the airflow distribution between them. Consequently, the additional resistance needed on each branch to adjust the airflow must be corrected from time to time.

With current technology, the control of the airflow on each duct branch is very difficult. The ventilation systems are often positioned far away from the site access points, either underground or on the surface, usually requiring a long time to be reached. Therefore, it is difficult to check if the airflow in each duct branch is meeting requirements. Also, where the airflow in a duct branch is different from what is required, the adjustment of the damper is usually manual and carried out by trial and error. The ventilation ducts are usually positioned on the roof of the underground space to avoid collision from machinery, so the access to both the airflow measurement on the duct and adjustment of the damper is difficult due to the height, creating a potential safety or ergonomic hazard.

In some cases the drive panel is connected to the internet or to the internal network of the underground space, which allows the remote control of the fan speed through the variable frequency drive. However, the important parameters of operation of the fan and of the airflow in each duct branch are not available remotely. Therefore, even with network connection to the drive panel, people still have to travel to the fan and duct branches to perform the measurement and control of the ventilation parameters.

In view of the difficulties in the control of the ventilation system, the fans usually have to be oversized so that even when the system is not well adjusted, there is still enough airflow for each duct branch. This results in unnecessary cost on the fan and higher power consumption. The adjustment process can be made a little easier by using automated dampers that can be remotely adjusted. However, this requires that infrastructure for energy and command is installed on the underground space reaching the damper position, which can be very expensive to install. Furthermore, the ventilation system often has to be moved to a different location in the underground space after the work is completed on a given location. In this case the infrastructure for energy and command for automated dampers must also be installed at the new location, resulting in a more complex and expensive operation.

SUMMARY OF THE INVENTION

Accordingly, there is provided according to the invention, an underground ventilation system having a fan, a plurality of ducts situated for the delivery of air from the fan to one or more underground work spaces, automated flow control dampers located at each of the duct branches, a fan sensor module located at a fan inlet or outlet to detect one or more of velocity, pressure, temperature and humidity, a connection panel in electronic communication with the fan sensors and with each automated flow control damper and configured to exchange status and control information with the fan sensors and the automated flow control dampers. The system may also include a cabling system attached to each one of the plurality of ducts and connected at one end to the connection panel and connected at the other end to the automated flow control dampers. The system may also include at least one work space sensor located in each work space where ventilation is required. The system also includes a display and control system in electronic communication with the fan, the fan sensors, the automated flow control dampers, and the work space sensors via the connection panel.

The display and control system is configured to receive and process data from the fan sensor module, from the automated flow control dampers, and the work space sensors, and to send automated instructions for adjustment to the fan and/or to one or more of the automated flow control dampers based on predetermined thresholds between detected work space conditions and predetermined desired work space conditions. The connection panel can be integrated with the sensor module, with the drive panel or can be standalone. There may provided a vibration sensor situated to detect fan vibrations and/or a motor temperature sensor situated to detect fan motor temperature. The ducts may be segmented ducts in which case each duct segment and split piece contains cable connectors at each end to connect to the cabling system.

BRIEF DESCRIPTION OF DRAWINGS

The foregoing summary, as well as the following detailed description of the preferred invention, will be better understood when read in conjunction with the appended drawings. For the purposes of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:

FIG. 1 is an example of an underground ventilation system of the prior art.

FIG. 2 is another example of an underground ventilation system of the prior art.

FIG. 3 is yet another example of an underground ventilation system of the prior art.

FIG. 4 is a representation of an underground ventilation system according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is a novel ventilation system including integrated measurement and control devices. The ventilation system includes at least one fan, ducts for the passage/delivery of air, one or more automated flow control dampers, a fan sensor module, a connection panel, a signal and energy cabling system incorporated on the ducts, and a display and control software. In the case that there is only a single duct branch or that separate control of airflow in each branch is not necessary, the dampers can be eliminated. A representation of a ventilation system according to an embodiment of the invention is presented in FIG. 4.

The sensor module is positioned at the inlet or outlet of the fan and may include sensors for various air flow parameters such as velocity, pressure, temperature and humidity. It receives energy from the connection panel and sends the readings to the connection panel. Any typical sensor from the market can be used and typically they will have an AC or DC energy input and an analog or digital signal output. The sensor module can also be integrated with the fan casing for a more compact design.

The connection panel may be positioned on the outside of the fan or may be integrated with the sensor module or may be integrated with the drive panel. It contains a gateway device that receives output signals from the sensors and communicates with the drive panel via network connection. The connection panel also receives a signal from the dampers indicating its current position and sends a control signal for position adjustment. The connection panel also communicates with the display and control software sending the sensor data and receiving the control commands. The connection panel can also integrate the data from other sensors on the fan such as vibration and motor temperature and from the drive panel such as fan speed and consumed power. It can also integrate data from other sensors installed in the underground space such as concentration of pollutants, visibility, temperature, and humidity that can be used to determine the ventilation requirements and conditions of the underground space.

The signal and cabling system includes cables attached to the ducts and split pieces that transmit the communication between the sensor module and the dampers. It also includes cables connecting the sensor module to the connection panel and connecting the connection panel to the drive panel. The cabling system can have single core or multi-wire cables depending on the electrical power required on the sensors and dampers and depending on the signal output from sensors. The power cables can be separated from the signal cables or they can be one single cable with separated insulation and grounding. In the case of the ducts, the cabling system is fixed to the ducts so there is no additional infrastructure required in the underground space to connect the automated dampers to the connection panel. Depending on the damper power and control requirements, there may be a direct cable connection from each damper to the panel or a cable split can be added on the duct split piece in case some of the cables can be shared between more than one damper. Also, in the case of segmented ducts, the cables must include connectors on the ends of each duct segment and split piece so the ducts segments can be assembled individually and with a simple and easy connection process.

The display and control software processes the information received from the connection panel and can display and store the measured ventilation parameters such as air velocity, pressure, temperature and humidity for contemporaneous or later viewing. The display and control software allows the control of the ventilation system through the command of the automated damper position and through the fan speed on the variable frequency drive. A local Human Machine interface (HMI) can be installed on the drive panel or connection panel to allow local display and command of the control software. In case the drive panel is not connected to a network then a local HMI is mandatory. In case the drive panel is connected to a network, the software can be accessed from computers connected to the network. Additionally, where the network is connected to the Internet, the software can be accessed remotely from computers and mobile phones. An Internet connection also allows the use of cloud-based systems instead of local servers. The display and control software can allow the input of the ventilation system characteristics such as duct diameter, duct length, fan characteristics, number of split ducts, number of automated dampers, etc. The display and control software can also be integrated with other software in the underground space such as other ventilation systems or a central control software.

The ventilation system of the present invention has a number of advantages in comparison to the prior art. One advantage is that it is an integrated system allowing measurement and control of the ventilation system on each duct branch in real time. According to the present invention, the ventilation equipment doesn't have to be oversized for a given ventilation requirement. This results in lower required fan power and lower duct diameter which translates to lower initial cost and lower operating cost. On another advantage, for the same amount of power utilization, it is possible to supply more air on each duct branch or to increase the total length of the ducts in comparison to the present technology.

Additionally, with real time measurements and ability to control fan speed and damper position, the air flow in each duct branch may be controlled remotely, avoiding the necessity to have personnel going to the underground space for measurements and adjustments, waving time and cost. The use of data from other underground space sensors or control software also allows the implementation of a Ventilation on Demand (VOD) control where the airflow requirement on each duct branch is adjusted according to the number of people, equipment and pollution generated in each part of the underground space.

The ducts with integrated cabling system and connectors between the duct segments allow a simple and easy assembly of the system. This avoids the necessity of additional infrastructure installation on the underground space. Also, when the ducts are moved to a different underground space the cabling is transferred together so there is saving in material and manpower in comparison to the transfer of the fixed infrastructure that is required with the present technology. The ducts can be constructed by flexible or rigid materials such as fiber reinforced PVC canvas, metal or polymers sheets, or any other material that can support the duct internal pressure.

The display and control software can store the history data of all measured parameters so sudden changes or unwanted trends can be used to diagnose problems and identify failures on the ventilation system remotely without requiring personnel going to the underground space. With this, the maintenance procedures can be scheduled before failures occur, and in the event of a failure, the maintenance crews can move to the underground space already knowing the probable cause of the failure and have the proper tools and parts to perform the repair. Where the drive panel is connected to a network, the software can generate automatic alerts based on the measured parameters so operation and maintenance personnel for the underground space can take remedial action. In this case the software can send commands and receive data directly from the variable frequency drive or other drive on the drive panel.

The software can also use the measured data to generate additional information on the operation of the ventilation system through calculations or algorithms. For example, if the measured static pressure on the fan is higher than design parameters, a notification can be generated to the operator of the system indicating that the excessive duct length was installed on the ventilation system. As another example, given the measured airflow on the fan and position of each damper, the software can indicate the airflow on each duct branch. This information is very valuable to optimize the operation of the ventilation system to support the work carried out in the underground space.

Notwithstanding the specific embodiments, features, elements, combinations and sub-combinations disclosed herein, it is expressly considered and here disclosed that every single element, every single feature, and every combination and sub-combination thereof disclosed herein may be combined with every other element, feature, combination and sub-combination disclosed herein.

It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as outlined in the present disclosure and defined according to the broadest reasonable reading of the claims that follow, read in light of the present specification.